They came together because they were all “big beautiful women” — BBWs for short.

But by the time they disbanded, they were short one of those descriptors and — thanks to weight-loss surgery — many of those women who once celebrated their overweight bodies were no longer “big” at all.

The new hour-long “Independent Lens” documentary “All of Me,” premiering Monday at 10 p.m. on PBS, follows a group of Austin, Texas-based women for five years as they change their positions and decide to undergo weight-loss surgery.

One of the women, 62-year-old Dawn Brooks, who peaked at 415 pounds, spent much of her life working as an advocate for size acceptance. In the 1970s, she appeared nude as a supersize model for a variety of “Bridget in the Buff” products, including calendars, books and jigsaw puzzles. The publishing company behind “Bridget” thought they were making gag gifts, but the items’ popularity proved there was an entire market of men out there hungry for the taboo nudity of very large women.

“Basically, ‘Bridget’ was my way of being out there,” says Brooks. “I said, ‘You know, guys, don’t be ashamed.’ ”

Brooks came to the BBW group through her work with the National Association to Advance Fat Acceptance, which she has since fallen out with over the organization’s strong stance against weight-loss surgery.

In the beginning, the Austin BBWs were mostly supersized and proud. They’d come together to socialize with people like themselves. But after one member told the group she was having gallbladder surgery — only to return a month later having secretly undergone gastric bypass — attitudes in the group began to shift.

“After it was successful, I think everyone re-examined their position,” says Brooks.“Whether you choose weight-loss surgery or not, that’s a decision everyone needs to make for themselves.”

Brooks decided to get an adjustable gastric band, both for health reasons and the looming threat of immobility. She is now down to 260 pounds, a level at which she’s remained for eight months.

“I don’t think I was a hypocrite,” she says. “I was destined for a scooter and, for me, that lifestyle is not what I would want to choose.”

But for all the good it’s done for her health, the weight loss has had its consequences. She and her husband, Guy, a “fat admirer” — someone sexually aroused by supersized women — have separated, in part because he is no longer attracted to her.

Another BBW, Judy Sinclair, 53, had the opposite trajectory after she underwent gastric bypass. After hitting 425 pounds, she slimmed down to 245 pounds, but is currently at 260. Her success drew her and her husband, Marty, closer — and he decided to have the surgery himself last November.

“I think my husband is a little bit different than a lot of fat admirers,” she says. “He found me intelligent. He liked that I could carry on a conversation. He saw more in me than the way I looked.”

It all begs the question: Are these women who once joined a group to be around other big, beautiful women now proud to be a smaller size?

“I am what I am,” says Sinclair. “I’ve worked really hard on being more than what I look like. I’m not better or worse.”